Electrical control system for mining machinery



N. D. LEVIN April 11, 1933.

ELECTRICAL CONTROL SYSTEM FOR MINING MACHINERY Filed Dec. 5, 1929 Patented Apr. 11, 1933 UNITED STATES PATENT OFFICE.

NILS D. LEVIN, OF COLUMBUS, OHIO, ASSIGNOR TO THE JEFFREY MANUFACTURING COMPANY OF COLUMBUS, OHIO, A CORPORATION 01 OHIO ELECTRICAL CONTROL SYSTEM roa MINING MACHINERY Application filed December 3, 1929. Serial No. 411,334.

The present invention relates to electrical equipment for mining machines and the like, and has particular reference to a safety. installation whereby current maybe supplied to one or several electrically driven appliances in the mine through a single safety control appliance. 1 1

In conducting mining operations in a mine room worked on the short wall system, itis customary to transport the short wall machine into the room on a truck travelling over tracks laid into the room. The truck is ordinarily motor driven and is'supplied with electricity through a double conductor cable mounted on a reel, the ends of the cable being respectively connected to the main supply conductors at the room entry.. Upon arrival in the room, the mining machine is unloaded from the truck, the latter then serving as a base in the vicinity of which the machine may be maneuvered, a flexible conductor cable in connection with the reel cable leading from the truck to the mining machine for the supply of current to the motor of the latter. a

According to the present invention, I mount on the truck main line switches in both sides of the line, the switch in the positive side of the line being closed upon initial operation of a controller located on the mining machine, and further'I provide in the conductor cable between the truck and machine, a novel form of junction box into which other motor driven appliances may be connected. If the mining machine is not to beoperated, but some other instrumentality, such as a conveyor, which does not 1nvolve a controller, is to be used, I provide means whereby the circuit for closing the positive switch may be completed at at the j unction box.

The two line switches are furthermore, ac cording to my invention, under the control of an overload relay provided with a reset device actuated by a switch located at the junction box. l I

Inasmuch as the junction box is adapted to supply current to a number of instrumentalities, it includes a number of sockets adapted to be plugged into. To avoid the danger of short circuits at the junction box when not all of its sockets are plugged into, I provide dummy plugs which must be inserted in the vacant sockets before any current can pass through the junction box.

Since the objects and advantages ofthe present invention will be obvious from a description of an embodiment thereof, I shall proceed to describe it, without further reference to its general aspects, in connection with the specific embodiment shown in the accompanying drawing which illustrates a ty ical installation.

eferring to the drawing, reference numeral 1 designates a grounded negative main line conductor, and 2 the positive main line conductor. The negative conductor will ordinarily be a track rail, andthe positive conductor an overhead trolley wire. The reel cable comprises conductors 3 and 4, the former being engaged with the track rail and the latter with the overhead conductor at the room entry in the well understood manner. Conductor 3 is connected to a fixed .contact 5 of an electro-magnetic switch 5 through a blow-out coil 6. The switch 5 includes a movable contact,5 carried on a swingable armature arm 5 adapted to be moved upon energization of a magnet coil 5 to move contact 5 against contact 5 to complete a circuit from conductor 3 to a conductor 7.

Conductor 4 isiconnected through a blowout coil 8 to a fixed contact 9 of an electro magnetic switch 9, the latter including a swingable armature arm 9 carrying a contact 9", and moved upon energization of the magnet coil 9 to engage contacts 95 and 9" and thereby complete a circuit from conductor 4 to a conductor 10. Conductor 10 is in connection through a coil 11 of an overload relay 11 with a conductor 12. v

Conductors 7 and 12 lead to a terminal box 13 at one end of a flexible cable housing 14 and through the latter to a terminal box 15 at the other end thereof, whence they are led into a junction box 16 and respectively connected to negative and positive bus bars 17 and 18 therein. 7 j

The overload relay 11 includes a movable arm 11 adapted to connect contacts 11 and 11 this arm being movable under the influence of coil 11* to break circuit between the contacts upon overload in the line. The arm 11 is adapted'tobe reset by means of a reset magnet11 Contact 11 of the overload relay is in connection with conductor 4 through a conductor 19, and'contact 11 is infconnection with conductor 3 through a conductor 20 in which is interposed coil 59. of switch 5. A conductor 21 is connected into conductor 20, and has interposed therein coil 9? of switch 9. The other end of conductor 21 is passed through cable housing. 14 to the, junction box 15. l l

A conductor. 22. leadsfrom conductor 3 at switch 5 through housing 14 to-a contact point 23 at junction. box 16. A switch arm 24 is adapted upon movement to connect contact 23 withv contact 25. to-complete the connection of line 22 to conductor 4 through the coil. of reset magnet 11% Each of bus bars 17 and 18 is provided with a. plurality of contact tips 17 and 18?. Conductor. 21Iis led around. the bus bars and, in front of each tip 17 or 18 ,is provided with a gap in the nature of a socket adapted to be engaged by plugs 26 and 27 which form theterminals of main line conductors 28 and 29 passing through a flexible housing 30 to the mining machine designated as'a whole att31. I l 7 Plug 26 comprises an insulating bodyllongitudinally of which conductor 28. is passed to a connectersocket26 adapted to engage overa tip 17 of bus bar17 to connect conductors 7 and28. The insulating body of the plug is surrounded, as here shown, by. a

conductor strip 26 which, when the plug is engaged with the bus bar, is so positioned as to bridge agap in line 21. Plug 27 is similarly provided with a connecter socket 27a and' 'a "conductor strip 27 which latter is adapted to bridge a further. gap in line 21 when plug 27 is engaged with bus bar. 18.

It will. beseen that in order to energize coil- 9 of positive switch 9, a circuit must begcompleted through conductorr21 to the negative side of the line. As will be descr bQd, the completion of this circuit is acomp i hed by a C n o e o e on h mining machine, the'completed circuit inludinae uetor 2 d hr gh s ing30 andhaving atitsend a plug 33 adapted to be inserted; ina gap 3430f circuit 21.

Plug33 is preferably of a shape such asto prevent its insertion inany of'the gaps in line 21 oppositetips 17? or 18, andincludes aninsulating bodyjhaving a localized lateral contact33? towhich conductorf32 is con; nes d: P us 3 si sertabl n gap as to bring contact 33 into engagement with terminal 21 of line 21 i i I have shown each of bus bars 17 and 18 as provided with five connector tips,and line 21 as having a gap opposite each of these tips. It is obvious that plugs 26 and 27 will bridge only two of these gaps so that no circuit willbe completed up to contact 33 of plug 33. The remaining gaps, however,'a re adapted to be bridged as by plugs such as 3.6 in c ne t on W t he ce du tor of o r elec i ly Qpera e mining ma; chinery, or by dummy plugs such as 37 and 38 providedmerely. with contact strips for the purpose of bridging all open gaps in line 21. T

In case no machine is to be used involving a controller, and hence. conductor 32, provide a further dummy plug 39having a full: conductor strip 39 adapted to bridge gap. 34v so as to connectconductor21 tocondnctorl at the junction box, thus completing. thecirs cuit through coil 9}; 1f

On the mining machine 31, there is are, ranged a. controller, including a commutating cylinder 40, areverse. drum. 41 and a, i e-1 sistance 42 for the control of a motor 43. The cylinder. 40 ofthecontrol-ler has spacedpthereon two similar segments 40? and. 40 engageable upon movement of thefcontroller cylinder to its first position .withfixedfingers 40 and 40 Inthe second position of the cylinder, a, segment 40" is engaged with. a' finger. 40* while in thethird, fourth andfifth positions of the cylinder, segments 40?, 40? and 40? are successively engaged with fingers 40"., 40i'and' 40 to cut out successive sections of: resistance 42. It will be notedthat allthe segmentsof. the commutator are in electrical connection with each other.

The reverse drum has arrangedthereomso far as is of interest as regards a circuit illus trative of the present invention, apair of bridging plates 41 and 41 adapted-to bridge fixed fingers 41", 41%"41- and 41 respectively. Finger 41 is connectedwith finger40F by means of aconductor44p i Conductor 29 is in connection with one field winding43 of motor 43 and througha conductor 43? with the other field winding 43, and thence through a conductor 45 with finger 41. Finger "41 is in connection through a conductor 46 with a brushcooperating'with'the motor armature 43, while the other brush is in connection with finger 41 through a conductor 47'. Finger 40? is connected to resistance 42' by means of a con; ductor 4 8, the other end of the resistance being in connection with finger 4O through a conductor 49, the latter having a"blow-out coil 50 interposedtherein. Conductor 28 is in connection'withfingers 40 while conductor 1 32 is inconnection with finger 40 In describing theoperatio'n ofthe described apparatus, it will be assumed'th at switch arm 11? of the overload relay is. in disconnecting position as regardsconta cts "11 and llfl th at plugs 26 and 27 are respectively engaged with a tip 17 a and 18, that plug 33 is inserted in gap or socket 84, and that the remaining gaps in circuit 21 are bridged by means of the conductor strips of a suitable number of dummy plugs as 37 or 38. Switch arm 24 will now be moved to connect contacts 23 and 25, thereby completing circuit 22 through reset coil 11 thus bringing switch arm 11 across the contacts 11 and 11. Switch arm 24 is manually operated and upon release will be brought to inoperative position by means of a spring 24. The resetting of the overload relay connects conductors 19 and 20 across the line, thereby energizing coil 5 of switch 5, and bringing contact 5 against contact 5 to connect conductors 3 and 7. Switch 9 remains open.

Upon moving the cylinder of controller 40 to its first position, segments 40 and 40 will engage fingers 40 and 40 respectively, and it will be assumed that the reverse drum has been moved to bring bridging plates 41 and 41 into operative relation with fingers 41, 41 and 41 41, respectively. Conductor 7 is now in connection with conductor 28 through bus bar 17 and conductor 28 through finger 40, segment 40, segment 40, finger 40 conductor 48, resistance 42, conductor 49, blow-out coil 50, finger 40 conductor 44, finger 41*, plate 41*, finger 41, conductor 47, commutator 43, conductor 46, finger 41 plate 41, finger 41, conductor 45, field coil 43, conductor 43", field coil 43 conductor 29, bus bar 18, conductor 12, coil 11*, and conductor 10, is in connection with the contact 9" of switch 9. Upon the movement of the commutating cylinder to its second position, segment 40 is engaged with finger 40", thereby connecting conductor 32 which is in connection with the negative side of the line and conductor 21 which is in connection with the positive side of the line, thereby closing switch 9 on the positive side of the line and initiating rotation of motor 43. Further movements of the commutating cylinder serve to successively cut out sections of resistance 42 in the well known manner. Upon reverse rotation of the commutating cylinder, switch 9 will be opened as soon as segment 4O leaves finger 40*, and the positive side of the line will thus be broken. Under these conditions, only the negative side of the line is in connection with the controller, so that there will be no difierenceof potential between the fingers and its grounded casing, thus avoiding all danger of short circuiting. Upon the occurrenceof an overload, switch arm 11 is moved to off-position, so that the coils of both switches 5 and 9 are de energized, and the switches thus opened.

If apparatus not involving a controller is to be operated, plugs such as 35 and 36 will be engaged with tips 17 and 18, plug 39 will be engaged in gap 34, and the remaining gaps'in conductor 21 willbe bridged by means. ,of'dummy plugs, such as37 and 38 Upon throwing in switch arm- 24, switches 5 and 9 'willbe' simultaneously closed. If desired, however, switch arm 24 may be moved to close negative switch 5, and then plug 39 inserted to complete circuit 21 and close switch 9.

It will be understood that the described embodiment of my invention is illustrative only, and that my invention includes all arrangements falling within the terms of the following claims.

I claim 1. In apparatus of the class described,a junction box comprising a pair of bus bars, plugs engageable with said bars; each of said plugs comprising a body of insulating material, a conductor extending longitudinally of the body for connection with a bar, and a conductive strip extending between external points of the body and insulated thereby from the conductor; a second conductor having a plurality of gaps therein bridged by the conductive strips when the plugs are engage with the bars, and dummy plugs each comprising an insulating body and a conductive strip extending between external points of the body, said dummy plugs being disposable in any of said second conductor gaps not filled by the first-described plugs to bridge such gaps by means of their conductive strips.

2. In apparatus of the class described, a junction box comprising a pair of bus bars, plugs engageable with said bars; each of said plugs comprising a body of insulating material, a conductor extending longitudinally of the body for connection with a bar, and a conductive band encircling said body and insulated thereby from the said conductor; a second conductor having a plurality of gaps therein bridged by the conductive strips when the plugs are engaged with the bars, and dummy plugs each comprising an insulating body and a conductive band encircling the body, said dummy plugs being disposable in any of said second conductor gaps not filled by the first-described plugs to bridge such gaps by means of their conductive bands.

3. In apparatus of the class described, a junction box, a pair of bus bars in the junction box, a line conductor in connection with each of said bars, a conductor extending around said bars and having gaps therein, and plugs engageable with the bars and adapted to bridge said gaps to complete said conductor up to one of the line conductors at the junction box.

4. In apparatus of the class described, a junction box comprising a pair of bus bars, contacts carried by said bars, plugs engageable with said contacts, line conductors in connection with said bars, a conductor other than the line conductor having gaps therein,

' ai g ps n y1whfln he p u s are engagedw thsa n c s, i f 5;.v I1 1; appa 'at us oi the class described, 'a, jiunction bo x comprising a pair of bus bars, a plurality of plugs engageable With. each of said bans, line conductors in connection with said bars, a conductor other than the line conductors having gaps therein, and means carried by said plugs to bridge said gaps. 19 In testimony whereof I have hereunto-"set y ha i l NILSD'LEVIN. 

